RORγt-Raftlin1 complex regulates the pathogenicity of Th17 cells and colonic inflammation

Th17 cells that produce Interleukin IL-17 are pathogenic in many human diseases, including inflammatory bowel disease, but are, paradoxically, essential for maintaining the integrity of the intestinal barrier in a non-inflammatory state. However, the intracellular mechanisms that regulate distinct transcriptional profiles and functional diversity of Th17 cells remain unclear. Here we show Raftlin1, a lipid raft protein, specifically upregulates and forms a complex with RORγt in pathogenic Th17 cells. Disruption of the RORγt-Raftlin1 complex results in the reduction of pathogenic Th17 cells in response to Citrobacter rodentium; however, there is no effect on nonpathogenic Th17 cells in response to commensal segmented filamentous bacteria. Mechanistically, we show that Raftlin1 recruits distinct phospholipids to RORγt and promotes the pathogenicity of Th17 cells. Thus, we have identified a mechanism that drives the pathogenic function of Th17 cells, which could provide a platform for advanced therapeutic strategies to dampen Th17-mediated inflammatory diseases.


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Sex and gender were not considered in the study design. However, sex information along with other variables (like disease location, family history of inflammatory bowel disease, etc.) was collected at the time of informed consent. Sex and gender were not considered relevant to the study as the focus of the study was to understand the molecular mechanism of colonic inflammation.
Healthy Control: Race-White (6), Asian (1), Black or African American (3); Ethnicity-Hispanic (2) The study participants were recruited from the UT Southwestern Medical Center. Written informed consents were obtained from all patients that were recruited, without discrimination of any kind including gender, age, race, and nationality. Healthy controls were recruited which underwent colonoscopy for colorectal cancer screening/surveillance and showed no symptoms of inflammation. Active ulcerative colitis patients were recruited which had actively inflamed mucosa of the sigmoid colon based on endoscopic appearances.
The study protocol was approved by the Institutional Review Board of UT Southwestern Medical Center, Dallas, TX-75390 (STU 112010-130).
Sample size was determined based on the common standard in the field. n>3 mice/group were used and all the animal experiments were repeated thrice. The number of independent samples used in the experiment are reported in the figure legends.
We did not exclude any samples. Age and sex matched were used in all experiments. Reported in figure legends.
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We did not blind to group allocation during experiments and data analysis. However, we carried out all the experiments and analyses without any prior biases and in an objective, rigorous scientific way. Conclusions were made based on statistical significance of the data.  All the cell lines used in the study were obtained from commercial source and authenticated by the manufacturers (see manufacturer's website).
Tested negative for mycoplasma contamination.
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C57BL/6, Rag1-/-, Raftlin1-LLNSL of 8-10 weeks of age (male and female both) were used in this study. Genotypes were verified by PCR analysis. Mice were housed in a pathogen free facility at the UT Southwestern Medical Center, according to the Institutional Animal Care and Use Committee (IACUC). Standard conditions of dark/light cycle, ambient temperature and humidity were used as provided by IACUC.
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All animal procedures were performed in accordance with the approved protocols by the Institutional Animal Care and Use Committee (IACUC) of UT Southwestern Medical Center, Dallas, TX 75390. IACUC No.: 2019-102734, 2019-102735.